Quote

"If we and the rest of the backboned animals were to disappear overnight, the rest of the world would get on pretty well. But if the invertebrates were to disappear, the land's ecosystems would collapse."

David Attenborough

Thursday, July 7, 2011

I love a good mollusc dissection, and giant cephalopod anatomy is especially groovy. Check out this video of an educational dissection with awesome narration by Dr.Mark Norman from the Museum of Victoria. I wish I could have been there!

Wednesday, June 29, 2011

Sunday, June 19, 2011

Limpets are one of those animals which people struggle to see as animate creatures. They live life in slow motion but also they keep that lid-like shell clamped down most of the time we encounter them- its hard to believe that are really alive and not just lumps on the rocks. But speed them up a hundred times or so and they really spring into action!

Tuesday, June 14, 2011

I love molluscs. I love finding them. I love watching them. I love learning about them. And I love eating them. They could be the food of the future, efficiently converting unusable resources into nutritious meat for everyone. Marine mollusc farming is an awesome innovation which protects wild stocks from damaging over-harvesting. Sometime the methods used to harvest wild molluscs are damaging too- none more so than scallop dredging.

This shocking video from the UK graphically illustrates, aside from the gritty and low-quality nature of the catch, why we should all avoid buying scallops. (sure, its theoretically possible to get superior diver-caught scallops which do no damage to the seabed but I have never seen them for sale in Australia and only rarely in the UK).
So, don't reward this sort of environmental abuse with your money. Only buy sustainably harvested molluscs: for more information see the excellent Sustainable Seafood Guide from AMCS.

Thursday, June 9, 2011

Well, I've had a few complaints that its been over a month since the last post- not a good look for a weekly blog! Apologies for my tardyness. I've been busy overseas with less internet access than I anticipated. If its any consolation I had a few mollusc-related encounters while away which will lead to some cool posts in the future.
That promised post on mollusc intelligence is still in gestation. In the meantime...

On my return to glorious Central Australia the weather greeted me with 3 days of cloud and rain. Although temperatures were low there was some nocturnal snail activity around Alice Springs, including one of my favourite local desert pulmonates; the beautiful Blue Horned Snail Pleuroxia adcockiana. Little has been written about this animal but in one text it is given the common name 'Adcock's Land Snail', derived from the latin name no doubt. As is oft the case with desert snails few people have seen them alive in the wild. On viewing this species in action I am always struck by its unusual body colouring. I took this video last year and it is possibly the first ever of any 'Pleuro'. It really shows the animal at its best- nice shell sculpture, milky white body and those long blue tentacles.
Enjoy.

Thursday, April 28, 2011

Mollusc sensory perception is fascinating. In the past I have touched on the Chiton's bizarre magnetic tongues which serve as an in-built compass. Turns out their vision is pretty odd too.

Mollusc vision is a cool topic. We humans are pretty proud of our visual acuity but to be honest our abilities are kind of 'middle of the road' when compared to the vast spread of molluscan eye designs. Future posts will explore a range of eye-innovation throughout the phylum but today I'm going to focus (no pun intended) specifically on Chitons.

In this weeks edition of the science journal 'Current Biology' there is a great article on some research into the eyes of Chitons. Its been known (or guessed?) for hundreds of years that the dozens of black speckles across the Chiton's valves (armour plates) are simple eyes but it was presumed that due to their tiny size and simple build that they were purely for detecting light with no resolution ability at all. The animal's lack of a clear brain structure probably led many to believe that anything further than detecting presence and absence of light would be beyond their ability. Well, a simple experiment has proved this assumption to be wrong in the case of one Chiton species at least.

The experiment was simply to observe the Fuzzy Caribbean Chiton Acanthopleura granulata's response to an approaching dark object and compare this to a general raising or lowering of the ambient light level. (Coincidentally, Acanthopleura granulata is the mystery Chiton shown in last week's MolluscPOW post.) Chitons 'clamp down' in a defensive posture when they feel threatened and they consistently did this on the approach of an object but did not do so when the ambient light changed. This neatly proves that the animals could 'see' approaching objects rather than just react to the presence and absence of light.

These little Chiton eyes are unusual: they are made from a solid crystal made of Aragonite (a form of calcium), the same hard material their valves are built of. Solid lenses in eyes have traditionally been seen as inferior to protein eyes such as our own due to their inability to focus by changing shape. This is not entirely fair: solid crystal eyes have advantages. Variations in the cross section of the lens allow them to have two separate refractive indices, that is, be able to achieve focus both in air and in water and also have a good field of view allowing both near and far objects to be resolved. They are also extremely tough. Both of these features are clearly helpful for Chitons which spend their whole lives in and out of water and being assaulted by crashing waves and grinding sands.

Until reading about Chiton eyes I had been under the impression that the ancient arthropod group the trilobites were the only animals to have tried out solid crystal lenses in their eyes (Richard Fortey makes this claim in his otherwise excellent book 'Trilobite'). Interesting that the Chitons should have separately evolved 'eyes of rock', indicating that for some animal lifestyles at least this design has a lot to offer.

The experiment doesn't tell us much about the amount of detail the chitons can resolve, nor does it explain how the images from the dozens of little eyes are processed by the beast's internet-like nervous system. However it does make a step forward in understanding more about these awesome and poorly understood creatures. The fact that we get so much new information from such a simple experiment really spells out how much we have yet to learn about many of the less famous Molluscan Classes.

Wednesday, April 20, 2011

MolluscPOW has been very gastropod-heavy in recent weeks, not good for a blog about diversity! So, here is a groovy mollusc of an entirely different sort- a polyplacophoran.

Watch this Caribbean Chiton bulldoze a little tidepool winkle out of its way! Coming through! Annoyingly, there were no clues which species this one is. Any Polyplac fans out there in-the-know drop me a line!

There has been some exciting news in the world of Chiton research in recent weeks. More details to come in the next MolluscPOW post...

Tuesday, April 12, 2011

This is the second book review to appear on Mollusc POW and it wont be the last. I hope you readers are finding them of interest.

I have been yearning for years for a book to be written which finally does justice to snails. Something which would bridge the yawning gulf between the often obtuse science of malacology and the everyday experience people can have with land snails. A book which basically ‘sells’ snails to the masses and establishes them as the unforgettable lead characters in the ecological epic being played out in nature. A book which comes but rarely and penetrates the cultural life of people of all types, not simply nature-nerds or popular-science fans.

“The Sound of Wild Snail Eating” was not that book, and I found it hard to set my feelings of unreasonable disappointment aside as I read it. I was of course completely unfair- Bailey never set out to deliver a molluscan version of “A Brief History of Time”. She instead has crafted a neat package of malacological/biographical essays which have two themes at their core: her personal experience of suffering a degenerative neuro-skeletal illness, and the doings of a snail which hitch-hiked into her bedside in a pot plant.

Some reviewers have railed against the malady-focused content, harshly accusing Bailey of self-indulgence and irrelevance. I agree up to a point: “my illness” stories are usually only of any interest to the afflicted themselves. At times I found myself skipping paragraphs of medical content to get to the nourishing molluscan meat whilst cursing Bailey’s editor for not ruling with an iron fist. But not everyone is quite as misanthropic as myself so perhaps some readers out there will find this part of the narrative of interest? I wonder if the problem with this book is simply one of marketing- it may have achieved less criticism were it sold as a human-interest story with good mollusc content, rather than as a piece of molluscan nature-writing with lots of subjective medical content shoehorned in.

The actual snail-centered content is quality stuff. Although based in the USA, Bailey neatly avoids the parochiality which often infects American nature writing. The discussion of her personal journey from snail-ignoramus to snail-disciple is compelling. She clearly took the time to dig hard in search of background information on snails- the big-picture stuff about their evolution and biology, as well as the thoughts on matters molluscan from science giants such as Darwin which can be so hard to find casually. You may find some of her content slightly twee, but not disastrously so. Occasionally she does drift into relating factoids which have an inauthentic parroted quality to them, but who among us could do anything else when explaining the deuterostome/protostome split in the tree of life? The details of that obscure moment back in the Cambrian Era at which the molluscan and our own evolutionary heritage appear to diverge gives me headaches and I have struggled to explain it in my own words on several occasions. The real strength of the book for me is that she has a sympathy for the animals themselves as individuals which I strongly share yet is starkly missing from other works on the subject. On the whole Bailey does a good job of expressing the admiration she came to feel for her gastropod companion I can only hope that this moves the casual reader to look again at some of the smaller yet remarkable creatures we share our world with.

In conclusion I would say that “The Sound of Wild Snail Eating” is certainly an important tome in the regrettably small canon of popular (ie.non-specialist) writings on molluscs. It may have a future as a ‘gateway’ text, a book you loan to a potential new recruit to snail-fan-dom who would not be hooked-in by other, drier, fact-avalanche-styled efforts. It will also while away a few hours while you wait for the mollusc book to be written…

Monday, April 4, 2011

Field Guide Review: Tasmanian Land and Freshwater Molluscs by B.J. Smith and R.C. Kershaw

This is the first of what I intend to be a steady trickle of mollusc book reviews hosted here at MolluscPOW. As a field-focused zoologist I have a particular fondness for identification guides so I think it fitting that I begin with one of the best I have found in Malacology, an oldie but a goldie: Smith and Kershaw’s excellent field guide “Tasmanian Land and Freshwater Molluscs”.

I acquired this book a couple of years ago from a charming bookshop in Hobart for the quaintly anachronistic price of $5. I spent many a happy day with it snail hunting in the field. My appreciation of this little gem over time has grown steadily with use.

Its brown paper cover, monochrome illustrations and industrial typesetting have in my opinion passed the stage where they look simply dated. They have now taken on an air of retro-chic. It serves to emphasise that with this book you are not getting another style-over-content glossy stocking-filler such as passes for a field guide in many high street bookshops. This book means serious snail-business!

Published in 1981 as part of the University of Tasmania’s excellent “Fauna of Tasmania” series it describes itself as an illustrated checklist of the terrestrial and freshwater snails of the island. I don’t think this really does it justice- it has clear and effective keys and distribution maps. The illustrations by Rhyllis Plant are of a very high standard and are of great assistance when poring over animals in the field. The sections at the beginning of the book describing collecting and preserving techniques, biogeography of the species described. It also sports one of the best introductions to the jargon of snail anatomy and shell description I have yet found. It is simply one of the best simple field guides I have had the pleasure of using.

The information in the guide is distilled from the 1979 “Field Guide to the Non-Marine Molluscs of South-Eastern Australia” by the same authors- I have not come across a copy of this book but if it were of the same standard as the Tasmanian guide it will be very useful.

No doubt dear reader you are thinking that 1981 was a long time ago. Names and taxonomy of groups has changed over the years and no doubt there will be fair slice of the content of this little guide which would need revising to be current but I wouldn’t say this detracts from the utility of the book. For the intended purpose of empowering an amateur to set out in the wilds of Tas and name the snails they luck upon this book is as good today as it ever was. It would be a huge boon for malacology were regional guides of this standard available for other parts of the world- guides sufficiently geographically focused to be portable and dipped into quickly in the field.

Although other title’s in the series have gone out of print over the years, “Tasmanian Land and Freshwater Molluscs” remains in print for the time being. The University of Tasmania has a useful list of stockists on their website. I would strongly recommend this volume anyone with an interest in Tasmanian wildlife, Australian snail fauna or simply the art of producing a good simple field guide. Be warned though, inflation has taken its toll over the years: a new copy today now costs a whole $5.50!

Friday, April 1, 2011

The dead sunbleached shells of desert land snails make a tempting addition to the mating bower of a Western Bowerbird. This splendid structure was photographed near Mimili in the Everard Ranges, South Australia by Dennis Allely. The walls of the bower are woven from sticks, the green objects are mostly old eroded glass and Quandong Berries The snail species are possibly Sinumelon pedasum and/or S. mugravesi.
This part of South Australia is truly awash with hardy desert snail species. I visit the area fairly regularly and I always come away astounded by the quantity and diversity of the desert land snail fauna down there.

Monday, March 21, 2011

Its time for another ‘Blue fleet’ post. Last time I covered the carnivorous Nudibranch Glaucillawhich I encountered wrecked on a pacific coast beach after a large storm. Another predatory mollusc was among the jumble of stranded Physalia bluebottle jellyfish and sea slugs that day: violet sea snails, Janthina sp.

These stunning Gastropods secrete an adapted mucus from which they construct a bladder of bubbles. They then hang alongside this mechanical flotation device upside down and drift among the ‘blue fleet’ of Physalia, consuming one whenever the opportunity arrises. Like the Glaucilla they absorb the venom and blue colouration from the jellyfish and turn it to their advantage to deter predation. Even their shell is tainted with a blue so deep it looks violet- hence the english name Violet Sea Snail. When disturbed the live animals dumped a blob of violet coloured goop on me- presumably a dose of venom- it stained my skin for several hours.

On the day I took this photo I found two distinct forms of Janthina: one a classic form (as in the photo) with countershading (a dark upper side and a light underside- to disguise the animal from both above). Its shell was wider than it was tall. The other form was comparatively scarce and featured violet all-over and a very exaggerated whorl reminiscent of the Succinidae. The shell was significantly taller than it was wide. If anyone out there knows of any resources I can use to key these animals out please drop me line!

Unlike my fellow seaside-goers, I look forward to another good bluebottle wreck next time I go to coastal New South Wales. Perhaps with the help of a wetsuit to ward off the stingers I’ll manage some photos of our blue fleet stalkers at work in the ocean? Got to be worth a try!

Thursday, February 10, 2011

Even bigger than the 'giant squid' Architeuthis, the Colossal Squid Mesonychoteuthis hamiltoniis the current title holder for biggest mollusc (and invertebrate) on Earth. The biggest specimen was 10m long and about 500kg in weight but its thought this was a sub-adult animal so the final maximum could be much more. Its beak was significantly smaller than many found in sperm whale stomachs indicating that there are some real monsters down there waiting to be found. More cool stuff to come on Sperm Whales and Giant Squid in future posts- I promise!

Monday, February 7, 2011

Combing the newly-cast strandline on a storm-battered beach is possibly the most fun a nature fanatic can have on their own. NSW central coast this Christmas was especially good. The storms came one after another all week and I spent many an hour strolling the glistening sands of South West Rock's Main Beach. In past seasons this beach has thrown up many gems, once a magnificent Nautilus came bobbing ashore as I watched, but thats a story for another day.
On the best day of the week for wrecked sealife, I noticed tiny striped splodges mixed with the blue tentacles and wobbly bladders of the abundant Man'O'War jellyfish Physalia phisalis. (OK, OK, in Australia they are called Bluebottles, and they are not actually jellyfish but properly a zooid Siphonophore- happy now?) I happened to have a plastic tub with me (as you do). I filled it with seawater and popped one of the droopy splooges in. On hitting the water it sprung back to life- a shining perfect little nudibranch called Glaucilla marginata. In a flurry of excitement I took dozens of photos. These are special molluscs indeed- ruthless pelagic predators which stalk the wandering 'blue fleet' of Man'O'Wars. They are not the only molluscan hunters of these drifting stingers and further along the beach I found a couple of examples, but I'll save those for future posts.
The blue fleet is a remarkable community of creatures. Normally they ply their trade far offshore but as the Physalia blindly drift where the wind blows and all the others follow the whole lot are prone to being blown ashore.
Like many pelagic sea creatures Glaucilla and its close relative Glaucus are not restricted to any one sea area- they occur almost everywhere the sea is the right temperature for them. They float upside down (the photo here is of their belly) close to the surface tension and simply bump into their prey as they drift. They can be mobile if they find themselves stuck- flexing and wriggling in that sea-slug sort of way until free. The blue colour is said to be the accumulated venom from the zooid tentacles. This obviously works as a predation deterrent- beachcombing Silver Gulls carefully avoid them.
So, a carnivorous sea slug which sails the seven seas hunting a dangerous prey- surely that has to be the weirdest thing I found on the beach that day. Not so...

Wednesday, February 2, 2011

Time for another mollusc-murderer. This week its video of the remarkable snake Pareas iwasakii. These snakes are adapted to hunt meaty forest snails such as this Satsuma mercatoria. The relationship between this predator and prey neatly illustrates the role predators and prey role in shaping each other's evolution. A truly cool reptile.